D3: When I try to use a pseudopotential produced by casino2upf in PWSCF, then it stops and whines about not having been compiled with support for hybrid functionals. I didn’t specify a hybrid functional, so why?

The casino2upf utility marks any UPF files it creates as having been generated using Hartree-Fock (since they generally are). If you do not supply a value for the ‘input_dft‘ keyword in the `system’ section of the PWSCF input file, then PWSCF will attempt to use the functional specified in the pseudopotential file i.e. it will try to do a Hartree-Fock calculation, and — given that this is only possible with PWSCF if you compiled it having invoked ‘configure‘ with the ‘--enable-exx‘ flag — then the code may stop and whine about not having been compiled with support for hybrid functionals. This can be confusing. Solution: specify ‘input_dft‘ in the input file.